I don't know if you seen it before, but here's an explanation for the Query Cache. Query Cache. This helps when selects are identical. However, it is also best when the selected results are identical. If you run this on something that is constantly being updated (like stockmarket data), you will probably be missing newer stuff. On the other hand, if you have some stable set of data (like zip codes in the United States, versus whatever unchanging data is there), you will not need to worry much.